HOW TO: 修改RTC时钟

问题：通过调用linux 中的time.h中定义的库函数（gettimeofday & settimeofday）去获取和设置系统时间后，发现在i850设备重新启动后，我做的时间修改全部作废了。

 

原因：linux中的时间有两个，RTC时间 和 系统时间

 

系统时间是每次在系统启动过程中通过读取RTC时钟获得的，此后我们看到的系统显示时间既是这个系统时间，我们通过库函数去读取和修改的也是这个系统时间，这意味着RTC时间根本没有被修改，所以导致系统每次启动读取的时间都不是我们曾经设置的。

 

解决：直接在kernel中改时间！

//file path : /home/cpp/r7_new/kernel_imx/drivers/rtc/rtc-mc13892.c/* * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved. *//* * The code contained herein is licensed under the GNU General Public * License. You may obtain a copy of the GNU General Public License * Version 2 or later at the following locations: * * http://www.opensource.org/licenses/gpl-license.html * http://www.gnu.org/copyleft/gpl.html */#include <linux/rtc.h>#include <linux/module.h>#include <linux/platform_device.h>#include <linux/pmic_status.h>#include <linux/pmic_external.h>#define RTC_TIME_LSH0#define RTC_DAY_LSH0#define RTCALARM_TIME_LSH0#define RTCALARM_DAY_LSH0#define RTC_TIME_WID17#define RTC_DAY_WID15#define RTCALARM_TIME_WID17#define RTCALARM_DAY_WID15static unsigned long rtc_status;static int mxc_rtc_read_time(struct device *dev, struct rtc_time *tm);static int mxc_rtc_set_time(struct device *dev, struct rtc_time *tm);static int mxc_rtc_open(struct device *dev){if (test_and_set_bit(1, &rtc_status))return -EBUSY;return 0;}static void mxc_rtc_release(struct device *dev){clear_bit(1, &rtc_status);}static void print_rtc_status(struct rtc_time *tm){printk("rtc_time/t: %02d:%02d:%02d/n", tm->tm_hour, tm->tm_min, tm->tm_sec);printk("rtc_date/t: %04d-%02d-%02d/n", tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday);}static int mxc_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg){int ret = -1;struct rtc_time tm;switch (cmd) {case RTC_AIE_OFF:pr_debug("alarm off/n");CHECK_ERROR(pmic_write_reg(REG_RTC_ALARM, 0x100000, 0x100000));return 0;case RTC_AIE_ON:pr_debug("alarm on/n");CHECK_ERROR(pmic_write_reg(REG_RTC_ALARM, 0, 0x100000));return 0;//****************************************************************************************//add this code for calling RTC clock setting functioncase 1314:rtc_time_to_tm(arg, &tm);ret = mxc_rtc_set_time(dev, &tm);if(0==ret) {printk("RTC setting SUCCESS/n");ret = mxc_rtc_read_time(dev, &tm);if(0==ret) {printk("the current RCT time is :/n");print_rtc_status(&tm);}return 0;}elseprintk("RTC set time ERROR/n");//****************************************************************************************}return -ENOIOCTLCMD;}static int mxc_rtc_read_time(struct device *dev, struct rtc_time *tm){unsigned int tod_reg_val = 0;unsigned int day_reg_val = 0, day_reg_val2;unsigned int mask, value;unsigned long time;do {mask = BITFMASK(RTC_DAY);CHECK_ERROR(pmic_read_reg(REG_RTC_DAY, &value, mask));day_reg_val = BITFEXT(value, RTC_DAY);mask = BITFMASK(RTC_TIME);CHECK_ERROR(pmic_read_reg(REG_RTC_TIME, &value, mask));tod_reg_val = BITFEXT(value, RTC_TIME);mask = BITFMASK(RTC_DAY);CHECK_ERROR(pmic_read_reg(REG_RTC_DAY, &value, mask));day_reg_val2 = BITFEXT(value, RTC_DAY);} while (day_reg_val != day_reg_val2);time = (unsigned long)((unsigned long)(tod_reg_val & 0x0001FFFF) + (unsigned long)(day_reg_val * 86400));rtc_time_to_tm(time, tm);return 0;}static int mxc_rtc_set_time(struct device *dev, struct rtc_time *tm){unsigned int tod_reg_val = 0;unsigned int day_reg_val, day_reg_val2 = 0;unsigned int mask, value;unsigned long time;if (rtc_valid_tm(tm))return -1;rtc_tm_to_time(tm, &time);tod_reg_val = time % 86400;day_reg_val = time / 86400;do {mask = BITFMASK(RTC_DAY);value = BITFVAL(RTC_DAY, day_reg_val);CHECK_ERROR(pmic_write_reg(REG_RTC_DAY, value, mask));mask = BITFMASK(RTC_TIME);value = BITFVAL(RTC_TIME, tod_reg_val);CHECK_ERROR(pmic_write_reg(REG_RTC_TIME, value, mask));mask = BITFMASK(RTC_DAY);CHECK_ERROR(pmic_read_reg(REG_RTC_DAY, &value, mask));day_reg_val2 = BITFEXT(value, RTC_DAY);} while (day_reg_val != day_reg_val2);return 0;}static int mxc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm){unsigned int tod_reg_val = 0;unsigned int day_reg_val = 0;unsigned int mask, value;unsigned long time;mask = BITFMASK(RTCALARM_TIME);CHECK_ERROR(pmic_read_reg(REG_RTC_ALARM, &value, mask));tod_reg_val = BITFEXT(value, RTCALARM_TIME);mask = BITFMASK(RTCALARM_DAY);CHECK_ERROR(pmic_read_reg(REG_RTC_DAY_ALARM, &value, mask));day_reg_val = BITFEXT(value, RTCALARM_DAY);time = (unsigned long)((unsigned long)(tod_reg_val & 0x0001FFFF) + (unsigned long)(day_reg_val * 86400));rtc_time_to_tm(time, &(alrm->time));return 0;}static int mxc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm){unsigned int tod_reg_val = 0;unsigned int day_reg_val = 0;unsigned int mask, value;unsigned long time;if (rtc_valid_tm(&alrm->time))return -1;rtc_tm_to_time(&alrm->time, &time);tod_reg_val = time % 86400;day_reg_val = time / 86400;mask = BITFMASK(RTCALARM_TIME);value = BITFVAL(RTCALARM_TIME, tod_reg_val);CHECK_ERROR(pmic_write_reg(REG_RTC_ALARM, value, mask));mask = BITFMASK(RTCALARM_DAY);value = BITFVAL(RTCALARM_DAY, day_reg_val);CHECK_ERROR(pmic_write_reg(REG_RTC_DAY_ALARM, value, mask));return 0;}struct rtc_drv_data {struct rtc_device *rtc;pmic_event_callback_t event;};static struct rtc_class_ops mxc_rtc_ops = {.open = mxc_rtc_open,.release = mxc_rtc_release,.ioctl = mxc_rtc_ioctl,.read_time = mxc_rtc_read_time,.set_time = mxc_rtc_set_time,.read_alarm = mxc_rtc_read_alarm,.set_alarm = mxc_rtc_set_alarm,};static void mxc_rtc_alarm_int(void *data){struct rtc_drv_data *pdata = data;rtc_update_irq(pdata->rtc, 1, RTC_AF | RTC_IRQF);}static int mxc_rtc_probe(struct platform_device *pdev){struct rtc_drv_data *pdata = NULL;printk(KERN_INFO "mc13892 rtc probe start/n");pdata = kzalloc(sizeof(*pdata), GFP_KERNEL);if (!pdata)return -ENOMEM;pdata->event.func = mxc_rtc_alarm_int;pdata->event.param = pdata;CHECK_ERROR(pmic_event_subscribe(EVENT_TODAI, pdata->event));device_init_wakeup(&pdev->dev, 1);pdata->rtc = rtc_device_register(pdev->name, &pdev->dev, &mxc_rtc_ops, THIS_MODULE);platform_set_drvdata(pdev, pdata);if (IS_ERR(pdata->rtc))return -1;printk(KERN_INFO "mc13892 rtc probe succeed/n");return 0;}static int __exit mxc_rtc_remove(struct platform_device *pdev){struct rtc_drv_data *pdata = platform_get_drvdata(pdev);rtc_device_unregister(pdata->rtc);CHECK_ERROR(pmic_event_unsubscribe(EVENT_TODAI, pdata->event));return 0;}static struct platform_driver mxc_rtc_driver = {.driver = { .name = "pmic_rtc", },.probe = mxc_rtc_probe,.remove = __exit_p(mxc_rtc_remove),};static int __init mxc_rtc_init(void){return platform_driver_register(&mxc_rtc_driver);}static void __exit mxc_rtc_exit(void){platform_driver_unregister(&mxc_rtc_driver);}module_init(mxc_rtc_init);module_exit(mxc_rtc_exit);MODULE_AUTHOR("*********");MODULE_DESCRIPTION("MC13892 Realtime Clock Driver (RTC)");MODULE_LICENSE("GPL");//file end//-------------------------------------------------------------------------------------//file for test setting RTC:/*编译：~/gcc-4.1.2-glibc-2.5-nptl-3/arm-none-linux-gnueabi/bin/arm-none-linux-gnueabi-gcc -Wall test_pty_static.c -o test_pty_static.exe -static -I /home/cpp/new_andriod/kernel_imx/include */#include <sys/types.h>#include <sys/stat.h>#include <stdio.h>#include <stdlib.h>#include <fcntl.h>#include <errno.h>#include <unistd.h>#include <syslog.h>#include <string.h>#include <sys/wait.h>int main(){int fd_rtc = -1;char rtc_name[20] = "/dev/rtc0";int ret = -1;struct timeval tv;struct tm;fd_rtc = open(rtc_name, O_RDWR);if(0 > fd_rtc){printf("/nERROR : open file <%s> FAILURE. now exit/n", rtc_name);return -1;}printf("/nopen file <%s> SUCCECC, FD = %d/n", rtc_name, fd_rtc);//-----------------------ret = gettimeofday(&tv,NULL);if(ret == -1) {printf("gettimeofday ERROR: %s/n",strerror(errno));}printf("we get the time: %llu %d %s/n",tv.tv_sec, tv.tv_sec, ctime((time_t *)(&tv.tv_sec)));tv.tv_sec+=5000;//改变时间printf("NOW we will set time to %llu %s/n", tv.tv_sec, ctime((time_t *)(&tv.tv_sec)));ioctl(fd_rtc,1314,tv.tv_sec);close(fd_rtc);return 1;}